The Physical Activity Guidelines for Americans released in 2008 recommended that adults get at least 150 minutes of moderate—or 75 minutes of vigorous—physical activity each week, and that this activity be done in “chunks” of 10 minutes or more. However, the findings of a recent study have challenged this recommendation that exercise be done in chunks 10 minutes or longer.
Researchers looked at longitudinal data for 4,840 participants with an average age of 57. One advantage of their study is that physical activity was measured directly with an accelerometer rather than by less accurate self-report. Accelerometer data was collected for each of the participants, and researchers looked at the association of this recorded physical activity with mortality data 6.6 years later. For their analysis, the researchers categorized the physical activity into total moderate-to-vigorous activity; activity done in greater than 5-minute bouts; and activity done in greater than 10-minute bouts. They then grouped the participants according to the proportion of their total moderate-to-vigorous activity that was accumulated in 5- or 10-minute bouts.
Not surprisingly, for each of the three groups, greater physical activity was associated with significantly lower risk of mortality. However, greater proportions of physical activity done in bouts was not associated with any additional risk reduction. Compared to the quarter of participants with the smallest amount of moderate-to-vigorous activity, the reduced risk ranged from 60% for the next highest quarter to almost 80% reduced risk for the most physically active. When the researchers looked at total daily moderate-to-vigorous activity, they found that the positive benefits of such activity plateaued at about 100 minutes a day of such activity.
Particularly in light of the fact that over 30% of the participants had zero recorded physical activity bouts of greater than 10 minutes in the data collected, it becomes an important health message that moderate-to-vigorous physical activity will have benefits no matter how such activity is accomplished. This may be particularly relevant for those older adults for whom sustained, longer bouts of physical activity may be a challenge.
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